As semiconductor devices becomes more highly integrated, the area allocated for forming capacitors within the devices typically becomes reduced and therefore it may be difficult to obtain required capacitance levels. Also, it is difficult to form conventional NO or Ta.sub.2 O.sub.5 films having reduced thicknesses in order to increase capacitance levels. Even in the event a thin film can be formed, it may be difficult to secure the desired capacitance levels because the use of thin films may result in increased leakage currents. In order to solve the above problems, methods for shaping a storage electrode of a capacitor in three-dimensional cylinder or fin forms have been proposed. However, these methods for shaping storage electrodes may be difficult to apply to highly-integrated semiconductor devices.
Therefore, research into capacitors having dielectric layers comprising high dielectric materials such as BST and PZT and metal electrodes formed of platinum group elements that are compatible with these high dielectric materials, has been actively pursued. The thickness of a BST layer, which is a high dielectric material, should not exceed a predetermined level when using it as the capacitor dielectric material of a highly-integrated semiconductor device. As will be understood by those skilled in the art, integrated circuit capacitors typically require thermal treatment at high temperatures so that preferred crystalline properties of the dielectric layer and stable leakage current characteristics can be obtained. Therefore, the use of high dielectric layers and high temperature treatment of capacitor leads to the formation of capacitors with improved leakage current characteristics.
To address limitations associated with conventional methods, a method of processing a surface of a Ta.sub.2 O.sub.5 dielectric layer with a plasma or radical annealing technique using O.sub.2 is disclosed in an article by Y. Ohji et al. entitled "Ta.sub.2 O.sub.5 capacitors' dielectric material for Giga-bit DRAMs" IEDM, pp. 111-114 (1995). In particular, the Ohji et al. article discloses that hydrocarbon contamination can be oxidized and then eliminated using plasma or radical annealing. U.S. Pat. No. 5,305,178 to Binder et al. also discloses a technique of increasing the electrical breakdown strength of capacitors by exposing a capacitor dielectric to a low temperature, low pressure plasma. Notwithstanding these attempts, there continues to be a need for improved methods of forming capacitors for highly integrated circuits.